firewire: Implement proper transaction cancelation.

Drivers such as fw-sbp2 had no way to properly cancel in-progress
transactions, which could leave a pending transaction or an unset
packet in the low-level queues after kfree'ing the containing
structure. fw_cancel_transaction() lets drivers cancel a submitted
transaction.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/firewire/fw-ohci.c b/drivers/firewire/fw-ohci.c
index 02b2b69c8741..e6fa3496183e 100644
--- a/drivers/firewire/fw-ohci.c
+++ b/drivers/firewire/fw-ohci.c
@@ -79,6 +79,7 @@ struct at_context {
         struct fw_ohci *ohci;
         dma_addr_t descriptor_bus;
         dma_addr_t buffer_bus;
+        struct fw_packet *current_packet;
 
         struct list_head list;
 
@@ -489,6 +490,7 @@ at_context_setup_packet(struct at_context *ctx, struct list_head *list)
                           ctx->descriptor_bus | z);
                 reg_write(ctx->ohci, control_set(ctx->regs),
                           CONTEXT_RUN | CONTEXT_WAKE);
+                ctx->current_packet = packet;
         } else {
                 /* We dont return error codes from this function; all
                  * transmission errors are reported through the
@@ -524,6 +526,12 @@ static void at_context_tasklet(unsigned long data)
 
         at_context_stop(ctx);
 
+        /* If the head of the list isn't the packet that just got
+         * transmitted, the packet got cancelled before we finished
+         * transmitting it. */
+        if (ctx->current_packet != packet)
+                goto skip_to_next;
+
         if (packet->payload_length > 0) {
                 dma_unmap_single(ohci->card.device, packet->payload_bus,
                                  packet->payload_length, DMA_TO_DEVICE);
@@ -564,6 +572,7 @@ static void at_context_tasklet(unsigned long data)
         } else
                 complete_transmission(packet, evt - 16, &list);
 
+ skip_to_next:
         /* If more packets are queued, set up the next one. */
         if (!list_empty(&ctx->list))
                 at_context_setup_packet(ctx, &list);
@@ -1012,6 +1021,29 @@ static void ohci_send_response(struct fw_card *card, struct fw_packet *packet)
         at_context_transmit(&ohci->at_response_ctx, packet);
 }
 
+static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
+{
+        struct fw_ohci *ohci = fw_ohci(card);
+        LIST_HEAD(list);
+        unsigned long flags;
+
+        spin_lock_irqsave(&ohci->lock, flags);
+
+        if (packet->ack == 0) {
+                fw_notify("cancelling packet %p (header[0]=%08x)\n",
+                          packet, packet->header[0]);
+
+                complete_transmission(packet, RCODE_CANCELLED, &list);
+        }
+
+        spin_unlock_irqrestore(&ohci->lock, flags);
+
+        do_packet_callbacks(ohci, &list);
+
+        /* Return success if we actually cancelled something. */
+        return list_empty(&list) ? -ENOENT : 0;
+}
+
 static int
 ohci_enable_phys_dma(struct fw_card *card, int node_id, int generation)
 {
@@ -1339,6 +1371,7 @@ static const struct fw_card_driver ohci_driver = {
         .set_config_rom         = ohci_set_config_rom,
         .send_request           = ohci_send_request,
         .send_response          = ohci_send_response,
+        .cancel_packet          = ohci_cancel_packet,
         .enable_phys_dma        = ohci_enable_phys_dma,
 
         .allocate_iso_context   = ohci_allocate_iso_context,